Tom did not invent the estimative index. He was an early adoptor and has been perhaps its most active evangelist. What he advocates in your quoted post reflects his evolution out of the original idea; it has now become something entirly different. Estimative Index is at its heart a simple weekly flush and fill method with a set of recomended target ppms for refill parameters. The EI has always been a simplified method of introducing novices to aquatic plant supplementation. More advanced hobbiests are expected to fine tune in order to achieve a wide range of variations. I think your PPS system has more in common with the practice of these advanced hobbiests.Edward said:I am not sure if I understand. If daily dosers are not practicing Estimative Index procedures then what is this?
Here is an early estimative index artical by Steve Dixon: http://www.sfbaaps.com/reference/dixon_01_01.shtml
Of special interest is the precautionary statement that Dixon closes with. I think this may be the tank he mentions: http://showcase.aquatic-gardeners.org/2001.cgi?&op=showcase&category=0&vol=3&id=68
More about the estimative index's origins can be found in the APD archives circa 1998-2002. Steve Dixon prompts this investigation but many people contribute to its conclusions. If you trace the origins you will find that Tom Barr's success with large waterchanges and minimal supplementation was instrumental in changing the dominant PMDD thinking about P.
One major difference that I see in what APC practitioners recomend vs. classical EI is that they see the index as indicating minimum values and have escalated ppm recomendations. Tom Barr for example, can often be observed claiming that much higher ppm values will not have detrimental effects. This implies that excess is preferable to shortage. While these concentrations may not often produce noticable algae problems I have observed that they can be quite detrimental to the health of fish.
My personal husbandry practice has backed off of daily supplementation and now includes a rest day. It is as follows: 1st day - 1/4 tsp KNO3 + 1/4 tsp enema, 2nd day - 10 ml TMG, 3rd day - rest, repeat previous 3 day cycle, then on day seven do a 10 gal. WC with 1/4 tsp Epsom salt, 1/4 tsp CaCO3 and 10 ml TMG. Tank size is 60 gal with 190 watts of light for 10 hours. Fish health has improved.